Application of an optimization procedure in adsorptive stripping voltammetry for the determination of trace contaminant metals in aqueous medium

A procedure for the determination of the contaminant metal In(III) by differential pulse adsorptive stripping voltammetry (DPAdSV) using ammonium pyrrolidine dithiocarbamate (APDC) as a complexing agent, has been optimized. The selection of the experimental conditions was made using experimental design methodology by means of a robust regression method which allows the elimination of anomalous points. The detection limit obtained was 1.3×10^-9 mol dm^-3. Possible interferences from concomitant metal ions were evaluated. Among all the metals analyzed, only Cd(II) was found to create an interference. This fact made impossible to carry out the determination of In(III) in the presence of Cd(II) using a univariate calibration. This problem was solved using multivariate regression techniques such as partial least squares (PLS). The procedure was successfully applied to the determination of indium in different aqueous samples.